One problem when starting the engine is an undesirable reverse rotation of the crankshaft. Typical reasons for reverse rotation may be the movement of the vehicle with an engaged gear on a slope or a premature disconnect of the starter, in which case the stored energy of the compressed cylinder acts as a gas spring, rotating the engine in reverse. Once the engine rotates in reverse, if the reverse rotation is not detected, the correct assignment of injection and ignition for the engine controller is disrupted, causing the engine to rotate in reverse for a certain time.
The basic problem is that sampling of the crankshaft signal generated by an increment wheel having an inductive or magnetoresistive sensor does not include any direction of rotation information.
Different approaches for solving this problem are known from the related art:
U.S. Pat. No. 6,691,690 describes a method for detecting reverse rotation of an internal combustion engine having a crankshaft sensor and a camshaft sensor from the relationship between the crankshaft signal and the camshaft signal.
German Patent No. DE 19933844 describes a method for determining possible reverse rotation by analyzing the time of successive tooth increments.
Japanese Patent No. JP 2000136737 describes a method for establishing a relationship between the intake manifold pressure curve and the markings on the crankshaft and/or camshaft, and U.S. Pat. No. 5,079,945 describes the analysis of two crankshaft signals using two sensor wheels and thus two sensors.
Finally, as known from German Patent No. DE 19933845, an angle sensor measuring absolute values may be provided on the camshaft.
All known methods have considerable disadvantages. Thus, methods should be adapted to the engine using careful plausibility analysis of the signals taking into account different operating conditions to provide reliable results. Methods involving additional sensors on the crankshaft or camshaft are costly and require substantial modifications of the engine design. An object of the present invention is to achieve improved reverse rotation detection at the start of an internal combustion engine using incremental sensors.